Cardas Phono Cartridge


A while back I purchased a Rega P9 table that came with a Cardas Ruby cartridge.  I didn't know how much use was on the cartridge but it sounds great and is a much nicer cartridge then any I had used in the past.  This is really an expensive cartridge and I'm wondering how to know when it should be repaired?  Where do you send such a cartridge to be repaired once it is worn?  Thanks for any input that anyone can offer on this.  I know that it can be rebuilt by Sound Smith but that's not quite the same is repaired by Benz and I saw they don't offer that service any more.
redcarerra
Send it to Soundsmith. Benz doesnt do rebuilds anymore, only tradein/trade up. Not sure if you can even use it for trade up/in since its been modified by Cardas. If the suspension is shot, and Benz won't allow trade on it your going to have to get a new cartridge.  Good news is Soundsmith does great work with one year warranty. 
If you send it to Benz, be prepared to purchase an interim cartridge as turnaround is very slow.  It's a Benz Ruby cartridge is a myrtle wood shell.